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Update Sorting_Custom_2.md

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Siyong 2020-06-16 18:35:56 -07:00
parent b2187969e9
commit 527ce9698e
1 changed files with 21 additions and 6 deletions
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content/4_Silver/Sorting_Custom_2.md
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@ -38,6 +38,10 @@ There are 2 main ways to have a custom comparator in c++.
<!-- Tested -->
```cpp
#include <bits/stdc++.h>
using namespace std;
int randint(int low, int high) {return low+rand()%(high-low);}
struct Foo
{
int Bar;
@ -47,6 +51,7 @@ struct Foo
const int N = 8;
int main()
{
srand(69);
Foo a[N];
for(int i=0;i<N;++i) a[i] = Foo(randint(0, 20));
for(int i=0;i<N;++i) printf("(Foo: %2d) ", a[i].Bar); printf("\n");
@ -114,6 +119,10 @@ We can also use [lambda expressions](https://www.geeksforgeeks.org/lambda-expres
<!-- Tested -->
```cpp
#include <bits/stdc++.h>
using namespace std;
int randint(int low, int high) {return low+rand()%(high-low);}
struct Foo
{
int Bar;
@ -122,12 +131,14 @@ struct Foo
const int N = 8;
Foo a[N];
bool cmp1(Foo foo1, Foo foo2) {return foo1.Bar < foo2.Bar;}
function<void(Foo,Foo)> cmp2 = [](Foo foo1, Foo foo2) {return foo1.Bar < foo2.Bar;}; // lambda expression
// void(Foo,Foo) means that the function takes in two parameters of type Foo and returns void
// "function<void(Foo,Foo)>"" can be replaced with "auto"
function<bool(Foo,Foo)> cmp2 = [](Foo foo1, Foo foo2) {return foo1.Bar < foo2.Bar;}; // lambda expression
// bool(Foo,Foo) means that the function takes in two parameters of type Foo and returns bool
// "function<bool(Foo,Foo)>"" can be replaced with "auto"
int main()
{
srand(69);
printf("--- Method 1 ---\n");
for(int i=0;i<N;++i) a[i] = Foo(randint(0, 20));
for(int i=0;i<N;++i) printf("(Foo: %2d) ", a[i].Bar); printf("\n");
@ -221,11 +232,15 @@ Since you cannot overload operators for primitives, you must use custom comparat
<!-- Tested -->
```cpp
#include <bits/stdc++.h>
using namespace std;
const int N = 8;
int a[N], b[N] = {4,8,2,3,4,1,2,4};
int main() {
int main()
{
printf("--- Comparator 1 ---\n");
iota(a, a+N, 0); // a={0,1,2,3,4,5,6,7}
iota(a, a+N, 0);
sort(a, a+N, greater<int>());
//sort a in decreasing order
for(int i=0;i<N;++i) printf("a[%d] = %d\n", i, a[i]);
@ -292,4 +307,4 @@ int main() {
sort(begin(v),end(v));
for (auto e: v) cout << e.s.f << " " << e.s.s << " " << e.f << "\n";
}
```
```